Fermentative production of ophthalmic acid

Research aims Escherichia coli YggS is a highly conserved pyridoxal phosphate (PLP)-binding protein whose biochemical function is unknown. We found that a yggS-deficient E. coli s t ra in (ΔyggS ) accumulates an unusual metabol i te , ophthalmic ac id (γ-L-glutamyl-L-2-aminobutyryl-glycine, Fig. 1). This ∆yggS mutant is the first microorganism that accumulates high levels of ophthalmic acid. Ophthalmic acid is known to be an oxidative stress biomarker and a potent agonist of a calcium-sensing receptor that elicits the kokumi taste. Although ophthalmic acid has potential uses in research and industrial applications, it is currently very expensive, and no fermentative production method has been reported. In the present study, we tried to develop the first known fe rmenta t ive method for the product ion of ophthalmic ac id .